( function () {
/**
 * This class generates custom mipmaps for a roughness map by encoding the lost variation in the
 * normal map mip levels as increased roughness in the corresponding roughness mip levels. This
 * helps with rendering accuracy for MeshStandardMaterial, and also helps with anti-aliasing when
 * using PMREM. If the normal map is larger than the roughness map, the roughness map will be
 * enlarged to match the dimensions of the normal map.
 */

const _mipmapMaterial = _getMipmapMaterial();

const _mesh = new THREE.Mesh(new THREE.PlaneGeometry(2, 2), _mipmapMaterial);

const _flatCamera = new THREE.OrthographicCamera(0, 1, 0, 1, 0, 1);

let _tempTarget = null;
let _renderer = null;

class RoughnessMipmapper {
  constructor(renderer) {
    _renderer = renderer;

    _renderer.compile(_mesh, _flatCamera);
  }

  generateMipmaps(material) {
    if ('roughnessMap' in material === false) return;
    const {
      roughnessMap,
      normalMap
    } = material;
    if (roughnessMap === null || normalMap === null || !roughnessMap.generateMipmaps || material.userData.roughnessUpdated) return;
    material.userData.roughnessUpdated = true;
    let width = Math.max(roughnessMap.image.width, normalMap.image.width);
    let height = Math.max(roughnessMap.image.height, normalMap.image.height);
    if (!THREE.MathUtils.isPowerOfTwo(width) || !THREE.MathUtils.isPowerOfTwo(height)) return;

    const oldTarget = _renderer.getRenderTarget();

    const autoClear = _renderer.autoClear;
    _renderer.autoClear = false;

    if (_tempTarget === null || _tempTarget.width !== width || _tempTarget.height !== height) {
      if (_tempTarget !== null) _tempTarget.dispose();
      _tempTarget = new THREE.WebGLRenderTarget(width, height, {
        depthBuffer: false
      });
      _tempTarget.scissorTest = true;
    }

    if (width !== roughnessMap.image.width || height !== roughnessMap.image.height) {
      const params = {
        wrapS: roughnessMap.wrapS,
        wrapT: roughnessMap.wrapT,
        magFilter: roughnessMap.magFilter,
        minFilter: roughnessMap.minFilter,
        depthBuffer: false
      };
      const newRoughnessTarget = new THREE.WebGLRenderTarget(width, height, params);
      newRoughnessTarget.texture.generateMipmaps = true; // Setting the render target causes the memory to be allocated.

      _renderer.setRenderTarget(newRoughnessTarget);

      material.roughnessMap = newRoughnessTarget.texture;
      if (material.metalnessMap == roughnessMap) material.metalnessMap = material.roughnessMap;
      if (material.aoMap == roughnessMap) material.aoMap = material.roughnessMap; // Copy UV transform parameters

      material.roughnessMap.offset.copy(roughnessMap.offset);
      material.roughnessMap.repeat.copy(roughnessMap.repeat);
      material.roughnessMap.center.copy(roughnessMap.center);
      material.roughnessMap.rotation = roughnessMap.rotation;
      material.roughnessMap.matrixAutoUpdate = roughnessMap.matrixAutoUpdate;
      material.roughnessMap.matrix.copy(roughnessMap.matrix);
    }

    _mipmapMaterial.uniforms.roughnessMap.value = roughnessMap;
    _mipmapMaterial.uniforms.normalMap.value = normalMap;
    const position = new THREE.Vector2(0, 0);
    const texelSize = _mipmapMaterial.uniforms.texelSize.value;

    for (let mip = 0; width >= 1 && height >= 1; ++mip, width /= 2, height /= 2) {
      // Rendering to a mip level is not allowed in webGL1. Instead we must set
      // up a secondary texture to write the result to, then copy it back to the
      // proper mipmap level.
      texelSize.set(1.0 / width, 1.0 / height);
      if (mip == 0) texelSize.set(0.0, 0.0);

      _tempTarget.viewport.set(position.x, position.y, width, height);

      _tempTarget.scissor.set(position.x, position.y, width, height);

      _renderer.setRenderTarget(_tempTarget);

      _renderer.render(_mesh, _flatCamera);

      _renderer.copyFramebufferToTexture(position, material.roughnessMap, mip);

      _mipmapMaterial.uniforms.roughnessMap.value = material.roughnessMap;
    }

    if (roughnessMap !== material.roughnessMap) roughnessMap.dispose();

    _renderer.setRenderTarget(oldTarget);

    _renderer.autoClear = autoClear;
  }

  dispose() {
    _mipmapMaterial.dispose();

    _mesh.geometry.dispose();

    if (_tempTarget != null) _tempTarget.dispose();
  }

}

function _getMipmapMaterial() {
  const shaderMaterial = new THREE.RawShaderMaterial({
    uniforms: {
      roughnessMap: {
        value: null
      },
      normalMap: {
        value: null
      },
      texelSize: {
        value: new THREE.Vector2(1, 1)
      }
    },
    vertexShader:
    /* glsl */
    `
			precision mediump float;
			precision mediump int;

			attribute vec3 position;
			attribute vec2 uv;

			varying vec2 vUv;

			void main() {

				vUv = uv;

				gl_Position = vec4( position, 1.0 );

			}
		`,
    fragmentShader:
    /* glsl */
    `
			precision mediump float;
			precision mediump int;

			varying vec2 vUv;

			uniform sampler2D roughnessMap;
			uniform sampler2D normalMap;
			uniform vec2 texelSize;

			#define ENVMAP_TYPE_CUBE_UV

			vec4 envMapTexelToLinear( vec4 a ) { return a; }

			#include <cube_uv_reflection_fragment>

			float roughnessToVariance( float roughness ) {

				float variance = 0.0;

				if ( roughness >= r1 ) {

					variance = ( r0 - roughness ) * ( v1 - v0 ) / ( r0 - r1 ) + v0;

				} else if ( roughness >= r4 ) {

					variance = ( r1 - roughness ) * ( v4 - v1 ) / ( r1 - r4 ) + v1;

				} else if ( roughness >= r5 ) {

					variance = ( r4 - roughness ) * ( v5 - v4 ) / ( r4 - r5 ) + v4;

				} else {

					float roughness2 = roughness * roughness;

					variance = 1.79 * roughness2 * roughness2;

				}

				return variance;

			}

			float varianceToRoughness( float variance ) {

				float roughness = 0.0;

				if ( variance >= v1 ) {

					roughness = ( v0 - variance ) * ( r1 - r0 ) / ( v0 - v1 ) + r0;

				} else if ( variance >= v4 ) {

					roughness = ( v1 - variance ) * ( r4 - r1 ) / ( v1 - v4 ) + r1;

				} else if ( variance >= v5 ) {

					roughness = ( v4 - variance ) * ( r5 - r4 ) / ( v4 - v5 ) + r4;

				} else {

					roughness = pow( 0.559 * variance, 0.25 ); // 0.559 = 1.0 / 1.79

				}

				return roughness;

			}

			void main() {

				gl_FragColor = texture2D( roughnessMap, vUv, - 1.0 );

				if ( texelSize.x == 0.0 ) return;

				float roughness = gl_FragColor.g;

				float variance = roughnessToVariance( roughness );

				vec3 avgNormal;

				for ( float x = - 1.0; x < 2.0; x += 2.0 ) {

					for ( float y = - 1.0; y < 2.0; y += 2.0 ) {

						vec2 uv = vUv + vec2( x, y ) * 0.25 * texelSize;

						avgNormal += normalize( texture2D( normalMap, uv, - 1.0 ).xyz - 0.5 );

					}

				}

				variance += 1.0 - 0.25 * length( avgNormal );

				gl_FragColor.g = varianceToRoughness( variance );

			}
		`,
    blending: THREE.NoBlending,
    depthTest: false,
    depthWrite: false
  });
  shaderMaterial.type = 'RoughnessMipmapper';
  return shaderMaterial;
}

THREE.RoughnessMipmapper = RoughnessMipmapper;
} )();
